Space

Space

1. Stars: Large groups of ignited gases, formed when a nebula gets large enough that pressure and heat combust in space and form protostars, which then become stars.

   • Brown & Red Dwarfs: Long-lasting stars, far smaller than our sun
   • Intermediate-Mass Stars: Lasts about 10 billion years, between the size of our sun and up to 800% larger, core collapses when fuel runs out causing expansion, before becoming a white dwarf.
   • High-Mass Stars: 8-25x larger than our sun, consume fuel very fast and die quickly and violently, whereupon they become supernovas and then neutron stars, however if their mass is high enough they will become black holes, with high enough mass to consume light
   • Hertzsprung-Russel Diagram: An arrangement of stars by luminosity and temperature, 90% of which are in the main sequence
   • Apparent magnitude: The brightness of a star as seen from Earth
   • Star Cluster: A grouping of many stars

2. Telescope: Optical device used to magnify images, most frequently used to view objects that are great distances away

   • Refractor: A telescope that uses a shaped lens to focus light into a small point, then into an eyepiece
   • Reflector: A telescope that uses a shaped mirror to focus a large amount of light onto a small mirror, which reflects it into an eyepiece
   • Hubble Space Telescope: A large telescope in space that, unhindered by light pollution, can take pictures of stars, planets and galaxies many light years away.

3. Planets

   • Moon: The satellite that orbits Earth. It orbits once every 27.3 days, and always faces the Earth.
     • Moon Phases: The Moon occasionally passes through Earth's Shadow, causing only part of it to be visible. The phases of the moon are: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, waning crescent.
     • The Moon's gravity can cause a pull on water on Earth. These are called tides.
     • Lunar Eclipse: When the Earth blocks the Moon from the Sun, causing the Moon to be totally in Earth's shadow.
     • Solar Eclipse: When the Moon blocks a part of the Earth from the Sun, causing the part of the Earth to be dark as if it were night.
   • Revolution: An object's rotation around another object. Earth's revolution around the sun causes seasons, due to the Earth being tilted slightly on its axis, causing certain parts of the planet to be exposed to the sun more than others during certain times of year. One revolution on Earth takes one year.
   • Rotation: An object's rotation around its own axis. Earth's rotation causes its day-night cycle. One rotation on Earth takes 24 hours.
   • Satellites: Objects orbiting a planet, often man-made
     • Man-made satellites make use of ground stations that uplink data to them, and then they downlink that information to other stations within the satellite's footprint.
   • Inner Planets: Hot, rocky planets in the innermost region of the solar system, including Mercury, Venus, Mars and Earth.
   • Outer Planets: Cold, gas giants in the outermost region of the solar system, including Jupiter, Saturn and Neptune (and formerly Pluto.)

4. Astronomical Unit: A unit of distance equivalent to the distance between Earth and the Sun

5. Light Year: A unit of distance equivalent to the distance travelled by light over the course of one year

6. Constellations: Recognisable patterns of stars in the sky, like Orion. These change over the course of the seasons, due to Earth's rotation around the Sun.

7. Asterisms: Recognisable patterns of stars that are not one of the constellations, ex. Big Dipper

8. Galaxies: Huge expanses of stars, planets and nebulas

   • Galaxy Cluster: Many galaxies grouped close together
     • Galaxy Supercluster: Many galaxy clusters grouped close together